<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<!-- 消息提示 -->
<div th:if="${message}" class="alert" th:classappend="${alertClass}">
    <span th:text="${message}"></span>
</div>

<!-- 添加CSS样式 -->
<style>
    .alert {
        padding: 15px;
        margin-bottom: 20px;
        border-radius: 4px;
    }
    .alert-success {
        background-color: #d4edda;
        color: #155724;
        border: 1px solid #c3e6cb;
    }
    .alert-danger {
        background-color: #f8d7da;
        color: #721c24;
        border: 1px solid #f5c6cb;
    }
</style>
</body>
</html>
